Effect of tanshinone IIA on cardiomyocyte hypertrophy and apoptosis in spontaneously hypertensive rats

In the present study, the effects of tanshinone IIA (TSN) on the prevention of left ventricular hypertrophy (LVH) and apoptotic processes were observed in spontaneously hypertensive rats (SHRs). A total of 18 SHRs (age, 8 weeks) were randomly divided into three groups. The SHRs in the control group (group S8) were sacrificed at week 8 of the experiment. The SHRs in the treatment group (group D18) and the placebo group (group S18) were injected with TSN and distilled water (1 ml/kg body weight/day), respectively, for 10 weeks, commencing at week 8, and were subsequently sacrificed at week 18. The systolic blood pressure (SBP) and left ventricular mass index (LVMI) were determined. Using hematoxylin and eosin and van Gieson staining, together with immunohistological methods, cardiomyocyte size and diameter, collagen volume fraction (CVF) and perivascular circumferential area (PVCA) were measured. Evaluation of Bcl-2, Bax and p53 expression levels for apoptosis analysis was performed using western blotting. It was observed that the SBP, LVMI, cardiomyocyte size and diameter, CVF, PCVA and cardiomyocyte apoptosis index (Bax and p53 expression) were increased significantly in group S18 compared with group S8. However, Bcl-2 expression levels were decreased in group S18 compared with group S8. The administration of TSN in group D18 resulted in higher Bcl-2 expression levels and significantly decreased LVMI, cardiomyocyte size and diameter, CVF, PCVA, Bax and p53 expression levels compared with group S18. LVH and apoptosis of the cardiac tissues increased with the increasing age of the SHRs. TSN may inhibit the development of LVH and decrease the level of apoptosis in SHRs, possibly via the upregulation of Bcl-2 and the downregulation of Bax and p53 expression.